FRFP
Item #: NBST27NV-C
SKU:
Price range: $1,219.00 through $1,788.00
No chimney and no household power, and a fire finished on both faces. The Monessen Natural Blaze See-Through is a 27" vent-free gas log burner built for a two-sided fireplace, listed as an unvent...
No chimney and no household power, and a fire finished on both faces. The Monessen Natural Blaze See-Through is a 27" vent-free gas log burner built for a two-sided fireplace, listed as an unvented room heater and as a vented decorative log set: 39,000 BTU/hr on natural gas (26,000 minimum) or propane (30,000 minimum), a self-powered millivolt standing pilot lit with a piezo igniter, and a minimum fireplace opening of 32" wide, 19" deep and 21-1/2" high — and because a see-through opens into two rooms, both faces are front faces, so each one has to measure the full 32" wide. It ships as the burner with its grate assembly, on/off switch log, lava rock, rock wool, flex line and anchor screws; the NBST27-F see-through log set it requires is sold separately. from $1,219.
Choose it if you have — or are building — a see-through masonry fireplace, UL127 factory-built fireplace or a listed vent-free firebox such as Monessen's Lo-Rider See-Through, and you want one burner whose flame reads correctly from both rooms without a chimney run, a gas conversion or an electrical circuit. The opening needs 32" of width, 19" of depth and 21-1/2" of height — and since a see-through has a front on each side, Monessen's firebox table asks for the 32" of width at both faces, not just the one you measure from. The millivolt valve keeps working through a power outage and takes an on/off or thermostatic remote. Dual listing means that if a mantel or wall clearance cannot be met, the same burner runs vented with the damper open.
It is not right for a bedroom or bathroom — at 39,000 BTU/hr it is far above the 10,000 BTU/hr that unvented appliances are allowed there. It is not a primary heat source, it takes its combustion air from the room and puts about an ounce of water vapor into it per 1,000 BTU each hour, so a very tightly sealed house without added ventilation, or a room smaller than the manual's 50 cubic feet per 1,000 BTU/hr (1,950 cubic feet at full input), is the wrong place for it. It is not a single-sided burner: the log stack is built for a fireplace open on two faces, and a conventional fireplace shallower than 19" cannot take it. Nor is it a stand-alone appliance — without a masonry fireplace, a UL127 factory-built fireplace or a listed vent-free firebox that meets its minimum opening there is nothing to install it in, and a glass-door frame or lip rising more than 3" in front of the burner is not recommended by the manufacturer.
The fireplace or firebox opening must be at least 32" wide, 19" deep and 21-1/2" high, and because a see-through is open on two sides Monessen's minimum-firebox table prints the same 32" for the rear width as for the front — both faces are fronts, so both must clear 32". A glass-door frame in front of the burner changes the depth: no restriction needs 19", a 0"-3" lip needs 24", and anything taller is not recommended. Sidewalls stay 9" from the side of the opening and the ceiling 42" above it; the material above the opening must be non-combustible — 12" or more of it needs no hood, 8"-12" requires the optional CABL hood, less than 8" is not allowed. A combustible mantel sits 14" above the opening if it is 3" deep, 17" at 6", 20" at 9" and 23" at 12" (8", 11", 14" and 17" with the hood); if those cannot be met the burner runs vented with the damper open. Combustible flooring other than carpet or vinyl may come right to the opening, but no carpet or vinyl within 14" of the face, and vinyl running to the wall calls for 14" of floor protection or an opening raised 12". Gas pressure is 5.0"-10.0" w.c. inlet and 3.5" manifold on natural gas, 11.0"-13.0" and 10.0" on propane, through a 3/8" line to the right-rear inlet; the burner weighs 36 lb and anchors to the floor with two screws.
The opening must be at least 32" wide, 19" deep and 21-1/2" high. A see-through faces two rooms, so treat both sides as the front — Monessen's minimum-firebox table lists a 32" rear width next to the 32" front width, and the opening has to make that 32" on each face. If a glass-door frame or a recessed hearth stands up to 3" in front of the burner, plan on 24" of depth instead; anything taller than 3" is not recommended. Monessen pairs the set with its Lo-Rider See-Through vent-free firebox (LSTF36-B), whose price-book page lists this burner and the NBST27-F logs as the pieces that complete it; in any vent-free firebox the firebox maker's own clearances govern.
No chimney is needed for vent-free use: the burner is listed as an unvented room heater, and an ODS safety pilot shuts it off if room oxygen drops. The same burner is also listed as a vented gas log set — run with the chimney and damper open when a mantel or wall clearance cannot be met, or when you prefer to vent the moisture outside. Vented, the damper must stay open to the free area in the manual's tables (22.1 sq in at a 10 ft factory-built chimney, 33.8 sq in at a 6 ft masonry chimney), a thermostat is not allowed, and Massachusetts requires the damper permanently removed or welded open.
No household power is needed, and line voltage must never be wired to the valve. The millivolt valve is self-powered by its thermopile and the standing pilot lights with the built-in piezo igniter — no matches, no batteries — so the fire keeps working through a power outage. The decorative on/off switch log in the box runs it; an optional wall switch, thermostat (vent-free installs only) or battery remote wires to the same terminals, and the receiver's piggy-back terminal lets a remote and a wall switch share the valve.
That depends on how deep the mantel is: a combustible mantel 3" deep sits at least 14" above the fireplace opening, 6" deep at 17", 9" deep at 20" and 12" deep at 23" — or 8", 11", 14" and 17" with the optional CABL adjustable hood installed. The wall directly above the opening must be non-combustible (slate or marble at least 1/2" thick): 12" or more of it needs no hood, 8"-12" requires the hood, and less than 8" is not allowed. Sidewalls stay 9" from the side of the opening and the ceiling 42" above it. If a clearance cannot be met, the burner must be installed and run as a vented appliance with the chimney and damper open. Send us your mantel depth and we will check the table with you.
Both are rated 39,000 BTU/hr at full input, and the only differences are the minimum input (26,000 BTU/hr on natural gas, 30,000 on propane), the orifice, and the gas pressure the valve expects — 5.0"-10.0" w.c. inlet on natural gas, 11.0"-13.0" on propane, with an external regulator required for propane. Each burner is built for one gas and cannot be converted in the field, so choose the fuel that is piped to the fireplace. Some sooting on the logs is normal in use and tends to be more visible with propane.
Hearth & Home Technologies backs the Natural Blaze See-Through with its limited warranty: 5 years on the burner and logs, 2 years on valves, pilots and remotes, 1 year on other parts, transferable to a later owner of the home and printed in full on pages 4-5 of the manual.
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